Electrically controlled breathing apparatus



April 15, 1958 R. P. FINNEY, JR 2,830,583

ELECTRICALLY CONTROLLED BREATHING APPARATUS Filed Jan. 27 1956 5Sheets-Sheet l 68 INVENTOR,

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5 Sheets-Sheet 2 Filed Jan. 27, 1956 IE-E ATTORNEYS I 6 l l v INVENTOR)OXYGF/V April 15, 1958 FINNEY, JR 2,830,583

ELECTRICALLY CONTROLLED BREATHING APPARATUS Filed Jan; 27, 1956 I 5ShBQtS-ShGGt 3 ATTORNEYi IN VENTOR April 15, 1958 R. P. FINNEY, JR2,830,583

ELECTRICALLY CONTROLLED BREATHING APPARATUS Filed Jan. 2'7, 1956 5Sheets-Sheet 4 AAAAAAIAA I Ivvvvvvv Q) ATTORNEY r'April 15, 1958 R. P.FINNEY, JR- 2,830,583

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ATTORNEY-S 2,830,583 Patented Apr. 15, 1958 fiice A ELECTRICALLYCONTROLLED BREATHING APPARATUS Roy F. Finney, Jr., SheIbyVilXe,'Ind.,assignor of forty percent to Charles W. Bailey, Pompano Beach, Fla.

Application January 27,1956, Serial No. 561,820

' Claims. (Cl. 128-142) insuficient to supportlife, and where a portableselfcontained source of breathable air is desirable to permit freedom ofmovement; v I

In the following specification the apparatus is described as relatingparticularly to. under-water diving, but it is to be understood thatthis is not the sole utilization thereof. Referring particularly to-pnder-yvater diving, there are, at present, two commonly usedself-contained methods. -'of supplying oxygen todhegdiver topermit:underwater operation without conneeging lines to the surface. The firstmethod, commonly termed theself-contained recirculating method,employs'.a .clpsed; loop breathing unit in which pure-oxygen is breathedover and over again, the carbon dioxide resulting therefrom beingcontinuously absorbed chemically as needed and more oxygen being addedmanually as needed to compensate for that by the body. 'lhe majordisadvantage inherent in this method isthat pure oxygenmay' be poisonousunder sufi'icient pressure, and. the use of this. unit is therefore.limited to depths of about 35 feet or less. This method-is, however,very efficient, as nearlyall of the. gas carried. by the diveris-utilized,

The second: method, theself-contau'ned' throw-away method, uses air onlywhich permits its use to depths of several hundred feet without illeffect. Air is basically a mixture of approximately 79% nitrogen whichis breathed without being absorbed or changed, and 21% approximately ofoxygen, some of which is absorbed by the lungs at eachbreath. The greatdisadvantage of this throwaway type diving unit is that up to 96% of thecompressed air which must be carried by the diver is lost. All of thenitrogen comprising 79% of the total is lost, and nitrogen does notenter into respiration except to dilute the oxygen and prevent oxygenpoisoning. Also with the throw-away method up to 80% of the availableoxygen is exhaled into the surrounding water and also lost. I From theabove it is evident that while the throwaway method allows the divertogo much deeper, it wastes thegreat majority of his air.

A primary object of this invention. is to combine the advantage of boththe above units, using a closed recirculating: circuit with" its great'.efiiciency in the utilization of breathable gases and allowing the userto breathe air instead of pureoxygen and therebyachievemuch greaterdepths safely. Provision is made for an apparatus of the recirculatingtype in which the user breathes air or a mixture of oxygen and nitrogenapproximating that found in air; employing particularly a meansforautomatically replacing the oxygen consumed by the bod'y and a meansfor absorhing the carbon dioxide content-"of the breathable atmosphere.Devices have previously been made which allow a constant pre set flow ofoxygen to the divers breathable atmosphere, but this has been unsatisfactory since the oxygen requirement of a diver may in-- crease 10times, depending on how strenuously he exer= cises, the temperature ofthe water and other factors. The device herein described automaticallymeters the proper amount of oxygen into the closed system regardless ofthe changing oxygen requirements of the diver.

An additional object of the invention is the provision of a simplifiedand improved apparatus of this character which may readily be carried onthe back of a diver to simplify ascent and descent into relatively deepwater, without discomfort or danger.

Still another object of the invention resides in the provision of aWheatstone bridge type gas thermalconductiv-ity cell including anelectrical impulse means and other electrical device for the purpose ofautomatically regulating the oxygen relative to the air or nitrogensupply.

A more specific object of this invention is the provision of a method.and means whereby the chambers or compartments in the gasthermal-conductivity cell of the Wheatstone bridge are kept atsubstantially equal pressures while the external hydrostatic pressures,to which the gas pressures in the compartments are responsive, undergochanges corresponding with changes in depth of water; such equalizationof pressures being accomplished without mixing the gases in thecompartments, which compartments are non-communicative with each other.

An additional object of the invention resides in the provision of meanswhereby a mixture of an inert gas, such as helium in the ratio of aboutto 20% of oxygen may be employed in lieu of the conventional airmixture. The use of helium instead of nitrogen as the diluting gas hasnumerous advantages well known to those versed in the art of diving suchas prevention of both caisson disease and nitrogen narcosis.

Yet another object is the elimination of bubbles escaping from thedevice at each breath as with the throwaway type unit. These bubbles areundesirable since they give warning to an enemy when such diving devicesare used for military purposes and they scare fish when used for sportpurposes.

Still other objects reside in the combinations of elements, arrangementsof parts, and features of construction, all as will be more fullypointed out hereinafter and dis-closed in the accompanying drawingswherein there is shown a preferred embodiment of this inventive concept.

In the drawings:

Figure l is a partially schematic sectional view of one form of deviceembodying features of the instant in-- vention, the wiring between theelectrical elements being shown.

. Figure 2 is a schematic sectional view of certain of the interiorelements of the apparatus.

Figure 3 is a perspective view disclosing the outer assembly-of thedevice as applied to the person of a swimmer or the like.

Figure 4 is a rear elevational view of the device of Figure 3.

Figure 5 is a sectional view taken substantially along the line S-5 ofFigure 4.

Figure 6 is a diagrammatic schematic view of the electrieal circuitincorporated in this apparatus.

Figure 7 is a view of the gas thermal-conductivity cell showing thebridge resistance members and their location in the cell chambers.

Figure 8 is a side elevation ofthe gas' thermal-conductivity cell takenalong the line 8-8 of Figure 7.

Figure 9 is a cross sectional view taken along the line 9--9 of Figure 7showing also the port connections.

brackets 14 secure to the opposite side of the receptacle an oxygen tank16. From the upper sides of receptacle '11 extend an air inhalation tubeand an exhalation tube 21. The upper part of receptacle 11 is providedwith a supplemental member 17, having perforations 18, to permit theingress of water under pressure to a pressure susceptible water-tightair-containing bag' 19 (see Fig. 2). The oxygen tank 16 communicateswith the interior of receptacle 11 by means of a standard oxygen cut-offvalve 22 and pressure reduction valve 28 and flow adjustment valve 26,to be more fully described hereinafter, while the air tank 15correspondingly communicates with the interior of the receptacle bymeans of standard cut-off valve 23 and valve 25, the purpose of whichwill be more fully described hereinafter.

Having reference now to Figure 2, the pressure responsive bag 19 isadapted to be filled with air from tank 15.

The air passes through a manually controlled valve 25 and a tubularmember 27, which opens directly into the chamber receptacle 11, and fromthis receptacle the air goes into the bag 19 by way of port and itstubular member 39. Oxygen from tank 16 is supplied through a cut-olfvalve 22, pressure reduction valve 28, a flow adjustment valve 26', anda solenoid-controlled valve 29 and tube 30 to the bag 19. Air withdrawnfrom the bag 19 passes through a Venturi or other suitable arrange-'ment 31 to a flexible tube 20 and vents through a check valve 33 (Fig.2) to a face mask or mouth-piece 34. Exhaled air thence passes throughthe a check valve .35 and flexible tube 21 to a container 37, adapted toeliminate the carbon dioxide by means of any suitable chemical such assoda lime 38 and then through a tubular member 39 back to the bag 19 forreutilization.

Venturi tube 31 is closely joined to a Wheatstone bridge 42 adapted todetect, by means ofdifiering gas thermal conductivities theconcentration of oxygen relative to a suitable diluting gas such asnitrogen. Venturi tube 31 is adapted to draw a new quantity of air frombag 19 during each inhalation of the diver through bridge chamber 42A bymeans of a pair of tubular members 43. The Wheatstone bridge used in thethermal-conductivity cell, as best shown in Figures 2, 6, 7, 8, and 9comprises opposite pairs of resistance members 44A and 44B, the resistorpair 448 being enclosed in suitable connecting receptacles 428containing normal air while resistor pair 44A is enclosed in similarreceptacle 42A containing air drawn from Venturi tube and bag 19 asheretofore described. When the bridge is adjusted in a manner to be morefully described hereinafter a current flows through wires 45 and 46' tocurrent interrupter 47 and thence through wires 48 and 49 to analternating current amplifier 50 whose output causes relay 95 to cut oilelectrically operated gas valve 29. During respiration when the oxygenconcentration of bag 19 falls below that desired, the current from theWheatstone bridge decreases and the input and hence output of theamplifier 50 also decreases causing relay 95 to open solenoid type gasvalve 29 in oxygen line 30 transmitting additional oxygen to the systemto replenish the oxygen absorbed by the lungs. When the oxygenconcentration has risen to the desired degree the bridge output risescausing the solenoid valve 29 to shut the oxygen off. Electric currentto operate the bridge, interrupter, amplifier and solenoid is suppliedby suitable batteries 67, 68, 69, and 70. For purposes of explanation,the diagrams illustrate the use of a vac- U and solenoid valve 29.

uum tube alternating current amplifier of conventional design and aninterrupter to pulse the direct current from the bridge. A directcurrent amplifier, such as one using transistors, can readily be adoptedand is highly desirable because of its small size, low currentconsumption and the elimination of the interrupter.

It is to be noted that the oxygen inlet line is provided with a suitablepressure reduction valve 28 and gauge 6'1 and fiow control valve 26between oxygen tank 16 There are seen in Figure 1 suitable batteries asindicated at .67, which indicates a bridge battery while 68 discloses aninterrupter battery, 69 an amplifier battery, and 70 a solenoid battery.At 71 there is shown a small flexible rubber bag under no tension whichcontains the standard gas, either air or the above-mentioned mixture ofhelium-oxygen, connected by means of a tube 72 to the container 42B, incommunication with the standard legs of the bridge, thus maintaining thestandard legs of the bridge filled with the standard gas, and alsomaintaining an equal pressure on all four legs of the bridge. Thepressure on legs of the bridge in chamber 42A is maintained equalthrough the pathway from bridge chamber 42A up through tubular member 43to the Venturi tube 31, thence into bag 19 and thence through tubularmember 39 and port 40 into the interior of receptacle 11. This pressureequalization is freely transmitted through the flaccid rubber bag wall71 and through tubular member 72 to bridge chamber 42B. This maintenanceof equal pressure is important in that any increase in-the gas'pressureof one pair of legs over that in the other will affect the operation ofthe bridge and is highly undesirable. Rubber bag 71 assures thatchambers 42B are always'filled with a standard'gas such as air.

In Figure 1 there is disclosed-a means of precluding the admission ofmoisture'condensing in the outlet tube 21 from being readmitted to thesystem and comprises a washer 75 positioned interiorly of the tubularmember 21 and a by-pas tube 76', which in turn leads to a condensationchamber 77 provided with 'a spring biased valve 78 which is adapted toopen to release moisture from the trap 77 when the pressure inthe'system rises sutficiently to force the valve open against thepressure exteriorly thereof. There is also disclosed in Figure -1 a"standard oxygen fixture 80 including a manually operable valve 25,operated by a lever 82 to admit the air mixture initially into thesystem. Other uses of valve 25 are described hereinafter.

Figures 7, 8, and 9 disclose in some detail the arrangement of theWheatstone bridge type thermal-conductivity cell. The container 42surrounding the legs of the bridge is composed of a high heat conductingmaterial such as brass which serves to surround the legs with the samethermal environment. Bridge chambers 42A are interconnected by passageand bridge chambers 42B are connected by passage 101. The two pairs ofchambers are supplied with inlet and outlet tubular members 102 whichallow gases to be admitted. The resistance members 443 which arecommonly made of fine platinum wire are centered in their individualchambers 4213 by supports 104 which are insulated by suitable material105 (Fig. 8). One of the tubular members 102 of chambers 42B is pluggedafter this chamber and bag 71 are filled with the standard gas.

Figure 6 discloses in schematic form the electrical connection of thedevice. In practice, the Wheatstone bridge 42 detects changes in thethermal conductivity of gas mixtures, in this case oxygen and eithernitrogen or helium. All of these gases has difierent rates of thermalconductivity. A steady current from battery 67 is passed through alllegs of the bridge causing them to be heated. .With air in both pairs ofchambers the bridge is adjusted by variable resistance R until theoutput current in connections 45 and 46 is of some suitable value. Thisdirect current is pulsed by electrically operated vibration interrupter47 and is then passed through the primary 91 of a step-up transformergenerally indicated at 92. The alternating output of transformer 92 isfed into the control grid of a suitable pentode tube 93. The amplifierisotherwise of conventional alternating current type with a gain controlfollowing the first stage of amplification and a relay 95 in the finalplate circuit. The gain control is so adjusted that with air in bothpairs of bridge chambers 42A and 42B, the relay 95 just closes. Theclosing of relay 95 causes the solenoid coil 55 to be deenergized andthe solenoid operated gas valve 29 is cut off. The electric gas valve 28is normally closed when deenergized. When respiration begins and asoxygen is removed from the closed system by the lungs the increasinglyoxy gen poor air is drawn into chamber 42A by tubular members 43 andVenturi tube 31. (See Fig. 2.) Chamber 42B is kept filled with pure airat all times as previously described. The two detector legs 44A of thebridge, being new surrounded by nitrogen and less oxygen than is foundin air, begin to lose heat at a difierent rate than the two legs 44Bsurrounded by pure air. This heat. loss of legs 44A causes them tochange in temperature and, therefore, in resistance, which in turncauses a current decrease in the bridge output passing throughconnections 45 and 46. This decreased input to the amplifier produces adecreased output and relay 95 (Fig. 6) drops out or releases itsarmature. The release of the armature closes the solenoid coil 55circuit energizing the gas valve 29 and admitting oxygen to the systemto replace that removed in respiration. When the oxygen has risen to thesame relative concentration as that found in air, the bridge outputrises causing relay 95 to close and oxygen valve 29 to cut ofi. Thecycle is repeated over and over, always maintaining the relative oxygenconcentration close to a constant value.

The use of electronic amplification is needed with an oxygen-nitrogenmixture in the closed system since these two gases have close rates ofthermal conductivity and the bridge output is, therefore, quiteinsufiicient to operate the relay directly.

It should here be pointed out that the amplifier is necessary only whenair is employed in the system. When a mixture of 80% helium and 20%oxygen is employed no amplification is needed and the bridge output issufiicient to operate a moderately sensitive relay directly, because theditference in thermal conductivity is much greater with helium andoxygen than with nitrogen and oxygen and the bridge output isconsequently much greater. again and again in the closed system, thusincreasing'the efificiency from about 4% as found in the throw-away typebreathing device to nearly 80% and, since almost all the oxygen isutilized, the over-all efiiciency approaches 100%.

From the foregoing the use and function of the apparatus should now bereadily understandable. The device is first positioned on the back ofthe users and held in position by means of the shoulder straps 12 andthe face mask or mouthpiece 34 placed in position. Air is admitted tothe device by actuating manually controlled valve 25, the air passinginto container 11 and through open port 40 (Fig. 1) into the bag 19. Thegas bag is thus partly filled with air, and valve 25 is then closed. Thepressure inside the case is maintained at the same pressure as theoutside water regardless of depth since this pressure is transmittedfrom the water to the air in bag 19 and through port 46} (Fig. 1) to theinterior of the case 11. This makes it unnecessary for the water-tightcase to withstand the high pressure found at depths. Air is drawn frombag 19 on inhalation through the venturi tube 31, and thence to themouthpiece. A very small part of the gases passing through the venturiis diverted to the Wheatstone bridge cell 42, which is close to theVenturi. Thus samples of the bag gases or air are repeat- In thisdevice, the same nitrogen is breathed edly: carried through the twodetector legs 42A of the bridge. The other two legs are connected to theflexible rubber bag 71, which bag is partly collapsed, or at least notunder any tension or internal pressure. This bag keeps the legs of thebridge filled with the standard gas, and co-operates to maintain thefour legs at the same pressure. The air which is taken from the bag 19on inhalation, when exhaled, contains the same amount of nitrogen aswhen inhaled, plus carbon dioxide, and about one fourth less oxygen. Theexhaled air passes to container 37 and the carbon dioxide is thereabsorbed. The check valves 33 and 35 serve to control the direction ofthe air as exhaled and inhaled. The exhaled air then passes into thebreathing bag 19. After this cycle is repeated a few times, theconcentration of oxygen in bag 19 decreases slightly and causes enoughchange in the output of the Wheatstone bridge to actuate amplifier 50,causing solenoid 55 to open valve 29 and admit additional oxygen to thesystem. The valve 26 is pre-set so that the infiow of oxygen into theclosed system is at the same rate asthat used by the body at maximumexercise As the oxygen continues to flow into the bag 19 theconcentration rises and, when it has reached the desired degree, theWheatstone bridge again changes sutficiently in output and the solenoidvalve is shut off.

As a diver descends the external water pressure increases causing adecrease in the volume of the breathable gas in bag 19. As this occursthe diver uses lever valve 25 to add more air or other breathable gas tothe system to maintain an adequate volume. Buoyancy of the entire systemcan also be controlled to some extent by this means. As a diver ascendsthe external water pressure decreases and the volume of the gas in bag19 increases. When the limits of expansion of bag 19 have been passedthe pressure in the entire system begins to exceed the pressure of thesurrounding water. At this point spring biased valve 78 is forced openand any excess air is allowed to escape. The loss of this gas on ascentis the only time any gas is allowed to leave the closed system. Oxygenis supplied only as needed and the nitrogen in the air is used over andover since its only purpose is that of a diluting agent to preventoxygen poisonmg.

From the foregoing it will now be seen that there is herein provided anovel electrically controlled breathing apparatus, particularly adaptedfor under-water use which accomplishes all the objects of this inventionand others, including many advantages of great practical utility andcommercial importance.

Since many embodiments may be made of this inventive concept and sincemany modifications may be made in the embodiment hereinbefore shown anddescribed, it is to be understood that all matter herein is to beinterpreted merely as illustrative and not in a limited sense.

What I claim is:

1. An under water breathing apparatus comprising a closed respirationcircuit having a flexible breathing bag for exposure to external waterpressure when in use, an oxygen supply unit connected to said circuit, asupply unit of other breathing gas connected to said circuit, a flexiblegas container for exposure to external water pressure when in use andnon-communicative with said closed respiration circuit, electricallycontrolled means for regulating the supply of oxygen to said respirationcircuit, said means comprising a thermal conductivity cell of theWheatstone bridge type having a compartment in communication with saidclosed respiration circuit and containing at least one arm of theWheatstone bridge and another compartment non-communicative with thefirst-named compartment and in communication with said. flexible gascontainer and enclosing at least one other arm of the Wheatstone bridge,and electrically operated valve mechanism between the oxygen unit andrespiration circuit and responsive to change in E. M. F. across theWheatstone bridge.

2. An underwater breathing apparatus comprising a closed respirationcircuit containing a flexible breathing bag for exposure to externalwater pressure, a face piece, an inhaling conduit from said breathingbag to said face piece, an exhaling conduit from said face piece to saidbreathing bag, an oxygen supply unit, electrically controlled meansincluding a source of electricity, an electrically-operated gas valveand a Wheatstone bridge type thermal conductivity cell in said inhalingconduit and adapted to receive samples of inhaled gas at each inhalationfor controlling oxygen delivery from said supply unit to saidrespiration circuit, said cell having a closed compartment incommunication with a flexible gas container for exposure to externalwater pressure when in use and non-communicative with said closedrespiration circuit and containing one pair of alternate arms of theWheatstone bridge, another compartment of said cell being incommunication with the inhaling con duit of said closed respirationcircuit and containing the other pair of alternate arms of theWheatstone bridge, means for passing over the latter pair of alternatearms of the Wheatstone bridge, at each inhalation of the breathing gas,the sample of said breathing gas, and means for transmitting a change inthe E. M. F. across the Wheatstone bridge to the electrically-operativemechanism of said gas valve.

3. The combination claimed in claim 2, together with means in saidinhaling conduit for forcing, at each inhalation, a sample of thebreathing gas into the second-named compartment of the cell and over thealternate arms of the Wheatstone bridge therein.

4. The combination claimed in claim 2, together with means comprising aVenturi in said inhaling conduit for forcing, at each inhalation, asample of the breathing gas into the second-named compartment of thecell and over the alternate arms of the Wheatstone bridge therein.

5. The combination claimed in claim 2, together with means comprising aVenturi in said inhaling conduit for forcing, at each inhalation, asample of the breathing gas into the second-named compartment of thecell and over the alternate arms of the Wheatstone bridge therein, and

means in said exhaling conduit for removing CO from the exhaled gasbefore its return to said breathing bag.

References Cited in the tile of this patent UNITED STATES PATENTS1,783,451 Rabinowitch Dec. 2, 1930 2,323,675 Rand July 6, 1943 2,414,747Kirschbaum Jan. 21, 1947

